10. As shown in the figure, in △ABC, the heights of CD, BE and AF intersect at point O, then the three heights of △ BOC are line segments _ _ _ _ _ _ _. The first triangle is 3 1. In the figure below, () a, trapezoid b, diamond c, triangle d and square 2. As shown in the figure.
3. As shown in the figure, ∠BAD=∠CAD, AD⊥BC, vertical foot is point D, BD = CD. Do you know which line segments are the bisector, midline or height of which triangle?
4. As shown in Figure 5, in the isosceles triangle ABC, AB=AC, a median line BD on the waist divides the circumference of the isosceles triangle into two parts, 15 and 6, and then calculates the waist length and the bottom length of the isosceles triangle.
5. There is a triangular seed test base, as shown in the figure. Due to the introduction of four excellent varieties for comparative tests, this land needs to be divided into four pieces with equal areas. Please make more than two division schemes for you to choose (drawing description).
6. As shown in the figure, in △ABC, D and E are the midpoint of BC and AD respectively, and S△ABC=4cm2. Looking for S △ Abe. 7. As shown in the figure, in the acute angle △ABC, CD and BE are the heights of AB and AC respectively, and CD and BE intersect at point P, if ∠ A = 50.
8 As shown in Figure 7- 1-2-9, AD is the angular bisector of △ABC, and DE∨AB, DF∨AC, EF and AD intersect at point O. Is the angular bisector of △DEF DO? If yes, please give proof; If not, please explain why. The first triangle is 4 1. If one of the outer angles of a triangle is an acute angle, the triangle is _ _ _ _ _ _ _. 2. In △ABC, if ∠C-∠B=∠A, the smallest angle among the external angles of △ ABC is. X = _ _ _ _ _ _。 (1) (2) (3) 4. As shown in Figure 2, in △ABC, point D is on the extension line of BC, and point F is a point on the side of AB. If you extend CA to E and connect EF, then ∠ 1, ∠2, then ∠3 has a size relationship of _ _ _ _ _ _ _. 5. As shown in Figure 3, in △AB=AC, AE is the angular bisector, ∠ B = 52, ∠ C = 78. Find the degree of ∠AEB. 7. As shown in the figure, in △ ∠B and ∠D should be 30 and 20 respectively, and Uncle Li measured ∠ BCD = 142, so it is concluded that this part is unqualified. Can you tell the truth? 9.( 1) As shown in Figure 7-2-2( 1), find the degree of ∠A+∠B+∠C+∠D+∠E+∠F; (2) As shown in Figure 7-2-2-7(2), find the degree of ∠ A+∠ B+∠ C+∠ D+∠ E+∠ F. 。
1 1. As shown in the figure, BD and CD are the bisectors of the two outer corners of △ABC ∠CBE and ∠ BCF, respectively. Try to explore the quantitative relationship between ∠BDC and ∠ A. 13. An outer angle of a triangle is an acute angle. Then the shape of this triangle is () A. Acute triangle B. Oblique triangle C. Right triangle D. Uncertain 1+2x 04. The three sides of a triangle are 5, 1+2x, 8 respectively. The value range of x is _ _ _ _ _ _ _.15. As shown in the figure, BD is equally divided into ∠ABC, DA⊥AB, ∠ 1 = 60, ∠ BDC = 80, and the number of times to find ∠ C. The grade test of polygons in the first level of mathematics is 1 the bisector of triangles is () A. Straight line B. 2. As shown in the figure, the two corners of the covered triangle can't be () A. An acute angle and an obtuse angle B. Two acute angles C. An acute angle. A right angle D. Two obtuse angles 3. If one internal angle of a triangle is equal to the difference between the other two internal angles, the triangle is () A. Acute triangle B. Oblique triangle C. Right triangle D. Arbitrary triangle 4. There are two sticks with lengths of 4cm and 6cm respectively. Please find another small stick and make a triangle with these three sticks. Then the range of the length x of the third stick is x & lt6b4 < X & lt6 C. 2 & ltX & lt 10D . 6 & lt; X< 105. As shown in the figure, the degrees of the five corners of the five-pointed star on the national flag are the same, and the degree of each corner is () A.B.C.D.6. If two triangles with a common side are called a pair of * * * side triangles, there are () A.2 to B.3 to C.4 to D.6 to 7 in the * * * side triangle with BC as the common side. The three internal angles of an acute triangle are ∠A, ∠B and ∠ C. If, then, of the three angles, () A. There is no acute angle B. There are 1 acute angles C. There are two acute angles D. There are three acute angles BCD A8 ... As shown in the figure, the shape of an experimental field is a triangle (. A. Turn around 90 b. Turn around180 c. Turn around 270 d. Turn around 360 9. When the master installs the wooden door frame, in order to prevent deformation, as shown in the figure, two diagonal battens are often nailed. The principle of doing this is based on the nature of triangles. 10. As shown in the figure, the bisector extends to and intersects at this point. Xiao Min, who loves thinking, found the following rules when writing his homework: (1) If, then; (2) If yes, then; (3) If, then; According to the above law, if _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _, this triangle is .3. If all three sides of a triangle are long, then the circumference of the triangle is. 4. As shown in the figure, the paper △ABC is folded along the DE, and the point A falls on the point A'. Given that ∠ 1+∠ 2 = 100, then the size of ∠ a.
5. As shown in the figure, in △ABC, ∠ B = 32, ∠ C = 55, AD⊥BC in D and AE ∠BAC in E, find the degree of ∠EAD. 6. A yellow croaker weighs 2.854 kilograms and has two significant figures. () 7、 _____________。 8. As shown in the figure, ab ∥ CD, ∞= 45, ∠ D = ∠D=∠C, ∠ B = _ _ _ _ _ _ Washington D.C.
Ab91233 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● The above is the word "T" made by chess pieces. How many pieces does it take to put 1 in the first "t"? What about the second one? According to this rule, how many pieces does the "t" in 10 need? 3 what about the n th one?